Suction box



June 17,1930. Y E.H.STREETER 1,763,910

SUCTION BOX Filed May 9, 1929 INVENTOR Eda fl? 5f/"6efer ATTORNEYS Patented June 17, 1930 UNITED STATES PATENT OFF ICE EDWIN H. BTREETER, OF CLOQUET, MINNESOTA, ASSIGNOR TO WOOD CONVERSION COMPANY, OF- CLOQUET, MINNESOTA, A CORPORATION OF DELAWARE SUCTION BOX Application filed Kay 9, 1929. Serial No. 361,563.

In the manufacture of certain types of wall board, wood is reduced to a pulp or fiberless mass and water added thereto to form a slurry. This slurry, containing about 95 percent or 96 percent water'by dry weight, is flowed on to a screen and formed into a level and uniform layer. It is then passed through a press to remove a substantial portion of the water and form the pulp into sheets. The damp sheets are then passed throu h a dryer to reduce the water content to a out 8 percent, which is the desired water content in the final product.

A press particularly adapted for this pur- 5 pose 1s disclosed in the patent to Adam Ziska, J r.', No. 1,690,152, granted November 6, 1928. This press consists of a lower stationary platen, an-u per movable laten and suitable means or removing t e water that is extracted from the sheet during the pressing o oration. I have found that the ca acity o the press can be greatly increased i some of the water is removed from the stock before it reaches the press. It is necessary that the stock originally be sufiicientl fluid to flow properly so as to arrange itse f in a substantially uniform and level layer when it is delivered to the screen. However, as soon as the stock is arranged on the"screen, a substantial portion of the m 'sture may be removed before it reaches the press without injury to the product.. 1 Various means may purpose. as

be emplo ed for this A suction box may e arranged on the screen forwardly of the'press or'the stock may be assed through squeeze rolls to extract a portion of the moisture. The stock reaching the press with its moisture content reduced can be assed through the press in a produces an incipient felting of the fibers smaller space 0 time and as the entire operaand fiber aggregates and thus delivers the stock to the press in a better condition for producing dense, compact wall board.

My invention comprises the above described rocess wherein a liquid slurry of pulp is owed on to a screen and permitted to arrange itself in a substantially uniform and even layer, a ortion of the moisture removed substantia ly immediately and the pulp then pressed to further reduce the moisture content and form a sheet. It also comprises suitable apparatus including a .suction box arranged under the screen forwardly of the press and adapted toextract a substantial amount of moisture from the pulp after it has flowed on to the screen.

In the drawings I have illustrated, somewhat diagrammatically, one form of the invention.

Fig. l is a side elevation of a portion of the sheet forming apparatus showing the invention applied; and I Fig. 2 is an elevation of the suction her and associated. parts at right angles to Fig. 1.

Referring to the drawings the reference numeral 1 designates a screen which is preferablyof Fourdrinier wire forming an endless conveyor passing over suitable rolls or pulleys 2 arranged at opposite ends of the machine. Theroll at the right hand end of the machine is not shown but the operation of the screen will be understood by thos skilled in the art'. Additional guide rolls 3 may be arranged on the return flight of the screen and the 0 erative flight,-in which the pulp slurry is placed on the screen, may be provided with a plurality of supporting rolls 4. Arranged over the screen is a flow box 5 by means of which the pulp slurry is placed on the screen in a substantially uniform and even layer. Various types of apparatus may be em loyed for this purpose and in the drawings have merel diagrammatically illustrated the pulp fee ing means. The apparatus preferably employed for this purpose is the flow box disclosed and claimed in my copending application, serlal No. 159,834, filed January 8, 1927 (now patent No.1,? 12,852, granted May 14, 1929), which travels transversely of the screen during the intervals when the screen is at rest to deposit the pulp. A suitable deckle 6 is arranged at one end of the flow box and a movable deckle 7 is carried on the other end of the flow box traveling across the screen with the flow box and separating the pulp slurry into sheets 8.

The screen 1 is intermittently driven and is ada ted to pause for a predetermined time a er each movement, the movement of the screen being equal to the width of the layer of pulp deposited on the screen upon each reciprocationof the flow box. At a point beyond the flow box the screen passes through a press which is preferably of the type shownlinthe Ziska patent referred to above and consists of a frame 9 carrying a lower stationary platen 10 and an upper 1 movable platen 11. In order to simplify the pump or other'means for exhaustin disclosure of the present application the means for reciprocating the upper platen 11, the detailed construction of the platens whereby the water may be removed from the sheet and the details of applying suction and pressure to the sheet durmg the pressing operation are omitted as these features are clearly described in the Ziska patent.

' Immediately beneath the flow box I rovide a suction box 12 which is adapte to remove a considerable portion of the moisture from the pulp slurryafterit has been deposited on. the sheet in a substantially even and uniform layer, and before it is fed to the press. While the detailed construction ofthe suction box may vary it is air tight and is provided with a perforated top, preferably formedof a heavy plate of perforated brass over which the screen 1 passes. A plurality of drain pipes 13 are connected to the suctionbox and these ipes in turn are connected to a header 14. he header is in turn connected to a valve. casing 15 having a valve 16 communicating therewith and the other side of the. valve casing is connected to a suitable drain 17. The valve is shown as a reciprocating gate valve, but other typesof valves may be employed. The drain pipe 17 is also connected to a VaCUufiIl t e suction box. The application of suction is controlled by the valve 16 and this valve is in turn controlled by the movement of the upper platen of the press. A link 18 is connected to the valve stem and this link is in turn connected to one arm of a bell crank lever 19 which ispivoted at 20 on a bracket 21 carried by the frame of. a machine. A second bracket 22 is carried by the upper platen of the press and this bracket is provided with an elongated slot 23 adapted to receive a rod,or.pin '24; carried b link 25'- connected to the other arm of the ll crank lever 19. Bell crank lever 19 'is provided with an'arm adapted to receive a counterweight25.

In operation at each pause of the screen 1,'

one section of board is submitted to the pressing operation to reduce its moisture the opposite end of the screen by the flow box 5. As stated above, this pulp is in the form of a slurry containing 95 percent to 96 percent of moisture. Immediately after the pulp is arranged in a layer on the screen, a portion of the moisture is withdrawn by suction. applied to the suction box 12 to reduce the moisture content and enable the pressing operation to be more quickly performed. As stated above, this removal of moisture before pressing also smoothes the? top and bottom of the pulp layer and redis tributes some of the finer fibers so as to produce an improved product. It also produces;

an insipient felting of the fibers and fiber aggregates. With the parts in the position shown in Fig. 1 of the drawings, the platen 11 is in its uppermost position and the valve 16 is closed by weight 25 so that no suction is applied to the suction box. As the platen moves downwardly the valve remains in closed position until the upper end of the slot 23 contacts with the pin 24 and during the last part of the downward movement of the upper platen the link 25 is depressed turnin the bell cranklever 19 in a clockwise dlrection and o eningthe valve 16 to exhaust the suction ox and remove moisture from the pulp layer immediately-above the suction box, by suction. At the end of the downward movement of the platen '11, the pin 24 is in the uppermost position in the slot 23 and weight 25'is raised. 'As the platen 11 moves upwardly, weight 25 closes the valve during the first portion of the u ward movement. Pin 23 then stays at t e upper end of slot 24, until the valve is closed. During the latter part of the upward movement of platen 11, after the valve'has closed. the pin assumes the position intermediate the ends of the slot, shown in Fig. 1 of the drawings. This alternate opening and closing of the valve 16 is repeated upon each movement of the platen so that the layer of stock just deposited on the screen by the flow box is submitted to suction and a portion of the moisture removed therefrom before the pressing operation.

the screen between the platens of a press to withdraw additional moisture from the pulp slurry and form a sheet, and then drying the sheet to its final moisture content.

2. The process of making fiber board which comprises forming a slurry of pulp containing substantially percent of moisture, depositing the pulp on an intermittently movin screen in a layer, withdrawing a portion 0 the moisture therefrom, and feeding the screen between the platens of a press to withdraw additional moisture an form a sheet. a

1 3. The process of making fiber board which comprises forming a slurry of pulp containingsubstantially 95 percent of water,

depositing the pulp' on an intermittently moving screen n a layer, ap lying suction to thelayer of pulp to with raw a portion of the moisture therefrom, and then pressing thepulp layer to withdraw additional moisture and form a sheet.

4. Apparatus for making wall board comprising an intermittently moving screen, and

means adjacent the screen for applying suction to a layer of pulp on the screen.

5. Apparatus for making wall board comprising a screen, a press through which said screen passes, a suction box arranged forwardly of the press, and means controlled by the movement of the the suction box.

6. Apparatus for making wall board comprising a screen, a press through which said screen passes, a suction box arranged forwardly of the press, means controlled by the movement of the press for exhausting the suction box, a valve for controlling said suction box, and control means for said valve operatedby said press.

7. Apparatus for making wall board comprising a screen, a press through which said screen passes, a suction box arranged forwardly of the press, means controlled by the movement of the press for exhausting the suction box, a valve for cont-rolling said suction box, control means for said valve operated by said press, a pivoted lever connected to said valve and a link connecting said lever to a movable part of the press.

8. Apparatus for making wall board comprising a screen, means for depositing a layer of pulp on the screen, a suction box beneath the screen at the point where the layer of pulp is deposited, a press through which the screen is adapted to pass after the layer of pulp has been deposited thereon,

and control means for said suction box operatively connected to said press.

In testimony whereof I aflix my signature.

EDWIN H. STREETER.

press for exhausting. 

